The objective of this research is to investigate empirically the reliability and clinical validity of selected components of the DSM-III multiaxial system. The proposed investigation involves the initial assessment, tracking, and two follow-up evaluations six months apart of a sample of about 650 psychiatric patients falling into ten selected major diagnostic categories, out of the 1,000 psychiatric patients randomly sampled from those presenting for care at the Western Psychiatric Institute and Clinic (WPIC). The diagnostic axes to be evaluated are: I. Psychiatric syndromes, II. Personality disorders, III. Physical disorders, IV. Psychosocial stressors severity, V. Highest level of adapative functioning in the past year, and VI. Current functioning. The first five axes are part of DSM-III; the last is being used routinely at WPIC. The study will use WPIC's Clinical Information System as a framework and its fully implemented Initial Evaluation Form as the main evaluation instrument. The latter will be compared with the NIMH Diagnostic Interview Schedule regarding diagnostic concordance. The proposed evaluation will be based on the following criteria: 1) Reliability - a prerequisite for diagnostic validity and estimated by the agreement among clinicians independently diagnosing the same patients; 2) Descriptive validity - estimated in terms of homogeneity and distinctiveness of selected diagnostic categories and the coverage of a general psychiatric population afforded by a given axis; 3) Clinical usability - investigated regarding the perceived suitability and usefulness of a given diagnostic axis among experienced clinicians, and its actual use in the patient care process, and 4) Predictive validity - assessed regarding the stability of diagnostic categories and axes at follow-up and their ability to predict course and outcome variables. This project is embodied within a long-term program on the evaluation and sequential improvement of diagnostic systems, including alternative biological and psychosocial axes and new categorizations and axial arrangements. Also, international investigations of multiaxial systems will be conducted using the principal investigator's bicultural background.